I believe the answer is none as supported
From the 2011 SDK under Unsupported Customizations
Modifications to the Microsoft Dynamics CRM website (file and website settings). Custom solutions should be installed in a different website. This includes modifications to the file system access control lists (ACLs) of any files on the Microsoft Dynamics
CRM server.
http://msdn.microsoft.com/en-us/library/gg328350.aspx
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